John isn't a diligent student, for it is the third time he has been late, _isn't it_?
原句中文意思是：“约翰不是一个勤奋的学生,因为这是他第三次迟到,对吗?”
此题考查反意疑问句.for “因为”,起补充说明的作用,连接并列句,不是原因状语从句.反意疑问部分应当与后一个并列分句保持一致.it is the third 是后面并列句的主句,疑问部分由它决定,所以空格上填 isn't he.至于 he has been late 这一部分,它是一个从句,我认为它是定语从句,对疑问部分没有影响.
但愿你能理解.